Crystal Structure
Orthorhombic — isolated SiO₄ + Al octahedra cross-linked by F/OH.
Elemental Composition (by mass)
| Element | Mass % | Visual |
|---|---|---|
| O Oxygen | 34.77% | |
| Al Aluminum | 29.32% | |
| F Fluorine | 20.65% | |
| Si Silicon | 15.26% |
Computed from simplified end-member formula. Solid-solution series, water content, and trace substitutions cause real-world variation.
IMA Abbreviation (Whitney-Evans 2010)
Tpz
→ Topaz
Pegmatite indicator
Standard symbol from American Mineralogist (Whitney & Evans, 2010). Used in thin-section labeling, phase diagrams, and IMA-style species records.
⏳ Long-term Aging & Care Timeline
imperial topaz color fadeyears
Trigger: sunlight
Intervention: Sherry/imperial topaz may slowly lighten in sun. Blue topaz (irradiated) is generally stable.
Pronunciation
/ˈtoʊpæz/
↔ TOH-paz
two syllables (Greek)
Lapidary & Faceting Recommendations
Recommended cut:
oval
Also seen:
pear, emerald, cushion
Typical yield:
30% of rough
Perfect basal cleavage means avoid placing table parallel to {001}. Cleavage planes must be at ≥30° to table for safe wear.
Birthstone & Anniversary Gift Reference
November (modern, traditional, zodiac) — zodiac: Scorpio / Sagittarius
› Full birthstones registry
⚠ Safety & Handling
☼light-sensitivelow
Some imperial topaz fades slightly with extreme UV.
Handling: Diffused lighting OK.
Information provided in good faith. Consult local hazmat regulations for transport and disposal. Severely hazardous specimens may require special storage cabinets.
UV Fluorescence
SW (254 nm)
Yellow / orange
moderate
LW (365 nm)
Yellow
weak
Imperial topaz shows weak response; blue topaz often inert.
SW = shortwave (germicidal lamp). LW = longwave (blacklight). Response varies with locality, trace impurities, and treatment.
Famous specimens of this species
American Golden Topaz — 22892.5 ct
Largest faceted yellow topaz. 172 facets.
Origin: Minas Gerais, Brazil. Now at: Smithsonian NMNH. Recorded 1984.
El-Dorado Topaz — 31000 ct
World's largest faceted gem of any species.
Origin: Brazil. Now at: Private. Recorded 1984.
› Browse all famous specimens
Tenacity
Behavior:
brittle (cleaves)
Under stress:
Splits along basal {001}
Perfect basal cleavage means careful handling at the parting plane.
Luster
vitreous
Bright vitreous.
Color Cause (Chromophore)
Chromophore:
color centers + Cr
Mechanism:
irradiation + heat
Color produced:
blue / yellow / pink
Imperial topaz: Cr-related color center. Blue topaz: irradiation-heat treatment.
Diaphaneity (Transparency)
transparent
Imperial, blue, and colorless topaz all transparent.
Type Locality
(ancient term) — Egypt (Topazos Island)
Source: Pliny
› Browse all type localities
Magnetism
Category:
diamagnetic
Test result:
Slight repulsion
Al₂SiO₄(F,OH)₂; diamagnetic.
Test with rare-earth magnet (N42 or N52 neodymium). Suspend specimen on thread for sensitive paramagnetic detection. Diamagnetic minerals are weakly repelled (visible only with strong magnets like bismuth).
Diagnostic Field Tests
Cleavage→ Perfect basal — careful handling
Sharp tap along c-axis can split crystals.
⚠ Use dilute HCl (~10%) only on inconspicuous spots; rinse promptly. Smell-tests should be brief and ventilated. Taste-test ONLY halite/sylvite — never lead, arsenic, or sulfur minerals.
Specific Gravity
3.49–3.57
g/cm³
medium
Heavier than quartz; lighter than corundum.
For comparison: water = 1.00, glass ≈ 2.5, quartz = 2.65, corundum ≈ 4.00, galena ≈ 7.50, gold ≈ 19.3.
Geological Setting
Environment:
pegmatite
Host rock:
granitic pegmatite, rhyolite, greisen
Companions:
Russian Urals topaz (Imperial topaz) comes from greisens around tin-tungsten deposits.
Treatments & Enhancements
Irradiation + heatuniversalstable· detection: hard
Colorless topaz irradiated then heated produces "Swiss blue", "London blue". Trade-standard, accepted.
Coatingoccasionalunstable· detection: easy
"Mystic topaz" — surface metallic coating gives rainbow color. Coating wears off with use; must be disclosed.
As a buyer: request written disclosure of treatments and confirm whether the price reflects treated or untreated material.
Characteristic Inclusions
Two-phase inclusionstwo-phase
Long needle-like cavities with liquid + bubble.
Negative crystalsnegative
Cavities mirroring host crystal habit.
★ Diagnostic inclusions are characteristic enough to help identify origin or species under 10× loupe.
Care notesStable but has perfect cleavage — avoid mechanical shock. No ultrasonic cleaning. Full cleaning guide →
Formation eraGranite-pegmatite + greisen; Russian Urals topaz Mesozoic.
Pleochroism (dichroic)
Axis o
colorless / paler
Axis e
characteristic body color
Strength: weak to moderate
Imperial topaz shows yellow-pink dichroism most clearly.
Cleavage & Fracture
Cleavage:
perfect 1 direction {001} — basal
Fracture:
subconchoidal
Perfect basal cleavage — important when cutting.
Market availability: Uncommon
Found at major shows and select dealers. Quality varies by locality.
Collector tier: Cabinet Classic
Display species collected for cabinet presentation, with specimens recorded from named localities.
Mohs 8
Vickers (~) 1650 HV
Knoop (~) 1340 HK
Nickel–Strunz
9.AF.35Dana
52.03.01.01Geological setting
Pegmatite
Diagnostic properties
Pyroelectric
Element composition by mass
Formula: Al2(SiO4)(F,OH)2 · molar mass: 182.05 g/mol
| O | 43.94% | |
| Al | 29.64% | |
| Si | 15.43% | |
| F | 10.44% | |
| H | 0.55% |
Computed from atomic weights (IUPAC 2021). Site-occupancy groups (Fe,Mn) split equally.
Mohs Hardness
8
Topaz sits at 8 on the Mohs scale — very hard; only diamond or corundum scratches it.
Colors:
Streak
White
White
Crystal system
Orthorhombic
Orthorhombic
Pronunciation/ˈtoʊpæz/
Type localitySchneckenstein, Saxony, Germany (classical)
Discovery First described 1737 by Johann Friedrich Henckel (Germany)
SilicatesSilicates – Nesosilicates
TL;DR · 1 min read
Topaz is the iconic Mohs-8 reference mineral and a Chinese Sichuan signature. The Xuebaoding district produces the world reference for translucent colorless and pale-blue topaz crystals on milky quartz, often paired with cassiterite and beryl.
Topaz is the iconic Mohs-8 reference mineral and a Chinese Sichuan signature. The Xuebaoding district produces the world reference for translucent colorless and pale-blue topaz crystals on milky quartz, often paired with cassiterite and beryl. Sichuan topaz – distinct from heat-treated commercial topaz – is the gem-collector standard.
Notable Varieties
- Imperial topaz (orange-pink)
- Sherry topaz (champagne)
- Sky-blue topaz
- Colorless topaz
The Chinese Angle
Xuebaoding Mine (Sichuan) is the world reference for collector-grade Chinese topaz – sharp pale-blue and colorless crystals on smoky quartz with cassiterite and beryl. Xianghualing in Hunan produces a secondary supply, often as smaller pale topaz crystals in pegmatite pockets. Both are untreated natural color.
Cite this entry
APA
MyMineralBox Editorial Team. (2026). Topaz. My Mineral Box. Retrieved May 23, 2026, from https://mymineralbox.com/mineral-encyclopedia/minerals/topaz/
MLA
MyMineralBox Editorial Team. "Topaz." My Mineral Box, 2026, https://mymineralbox.com/mineral-encyclopedia/minerals/topaz/. Accessed May 23, 2026.
Chicago
MyMineralBox Editorial Team. "Topaz." My Mineral Box. Last modified May 3, 2026. https://mymineralbox.com/mineral-encyclopedia/minerals/topaz/.
BibTeX
@misc{mmb_topaz,
author = {{MyMineralBox Editorial Team}},
title = {{Topaz}},
year = {2026},
publisher = {My Mineral Box},
url = {https://mymineralbox.com/mineral-encyclopedia/minerals/topaz/},
urldate = {2026-05-23}
}